Balanced amplifier arrangement for power control and improved deep back-off efficiency

ABSTRACT

Methods and apparatuses for providing a reduction in output power of a balanced amplifier configuration are presented. According to one aspect, reduction of the output power is provided by deactivating one of the two amplification paths of the balanced amplifier. According to another aspect, impedances seen at ports of input and output couplers of the balanced amplifier configuration part of a deactivated amplification path are selectively switched in dependence of operation according to the reduced output power or according to normal output power. In addition, or in the alternative, impedance seen at an isolated/terminated port of the input and/or the output coupler is selectively switched in dependence of the operation. When operating according to the reduced output power, values of the switched impedances can be adjusted to tune a frequency response of the balanced amplifier.

TECHNICAL FIELD

The present teachings relate to radio frequency (RF) circuits. Moreparticularly, the present teachings relate to methods and apparatusesfor power control with improved efficiency of balanced amplifiersoperating in power back-off conditions.

BACKGROUND

FIG. 1A shows a simplified bock diagram of a prior art balancedamplifier (100A) that can be used, for example, in a radio frequency(RF) transmit path of an RF system. The balanced amplifier (100A) isconfigured to amplify an input RF signal, RF_(IN), to generate therefroman amplified version of the input RF signal, RF_(OUT), which can be usedfor transmission via, for example, an antenna (150) of the RF system. Asshown in FIG. 1A, amplification of the RF_(IN) signal may be providedvia separate amplification paths (shown in the figure as a solid pathand a dashed path) of the balanced amplifier (100A), each suchamplification path comprising respective (single-ended) amplifiers (130a, 130 b) that may operate on phase-shifted versions of the RF_(IN)signal. For example, the amplifiers (130 a, 130 b) may operate inquadrature (i.e., 90 degrees apart), or in other words, theyprocess/amplify RF signals of (substantially) same power but inquadrature phase.

As shown in FIG. 1A, an input coupler (110) (e.g., a quadrature coupler,a branch-line coupler, etc.) of the balanced amplifier (100A) splits theinput RF signal, RF_(IN), provided at a (input) port P1 of the inputcoupler (110), to two quadrature signals (i.e., 90 degrees apart) ofsubstantially same power (e.g., amplitude) at respective (output) portsP3 and P2. The split quadrature signals at the ports (P3, P2) of theinput coupler (110) are fed to the respective amplifiers (130 a, 130 b)for amplification and output to respective (input) ports (P2, P3) of anoutput coupler (120). In turn, the output coupler (120) constructivelycombines the two phase-shifted (quadrature) signals provided at theports (P2, P3) of the output coupler (120) to generate therefrom acombined output RF signal, RF_(OUT), at a (output) port P1 of the outputcoupler (120). Accordingly, the RF signal, RF_(OUT), output by thebalanced amplifier (100A) has a power that is substantially equal to thepower of the RF signal, RF_(IN), input to the balanced amplifier (100A)multiplied by the gain of the amplifier (e.g., gain of the amplifiers130 a, 130 b).

A person skilled in the art knows the performance advantages of usingbalanced amplifiers, such as one shown in FIG. 1A, in a transmit path(and/or receive path) of an RF system, such benefits including, forexample, higher power handling, and higher immunity with respect to VSWR(voltage standing wave ratio) performance due to, for example, reducedlosses to reflections arising from mismatched amplifiers used insingle-ended configurations. Such increased tolerance to VSWR providedby balanced amplifiers makes such amplifiers an ideal choice for, forexample, mobile handsets, to counter effects of antenna impedancevariations due to different user hand-holdings of such handsets.Increased VSWR tolerances provided by such balanced amplifiers can alsoadvantageously be used, for example, in base stations used forbeamforming applications (e.g., millimeter wave 5G) wherein antennaimpedance provided via elements of a phase array to individualamplifiers participating in the beamforming can drastically vary.

The higher power handling that is inherent to the combining of the two(quadrature) amplified RF signals of the balanced amplifier (e.g., 100Aof FIG. 1A) allows for even higher output power (e.g., 3 dB or higher),and therefore makes balanced amplifiers an ideal choice in applicationswhere amplifiers are required to operate in power back-off conditionsdue to, for example, increased linearity demands. One such applicationis millimeter wave 5G, wherein corresponding wideband complex modulationschemes require amplifier linearity performances that can only beachieved when the amplifiers operate in power back-off conditions. Asknown to a person skilled in the art, amplifiers operating in powerback-off conditions are less efficient (dissipate more power) andtherefore generate more heat. Accordingly, cumulative effect ofoperating amplifiers participating in the beamforming (e.g., formillimeter wave 5G applications) in respective power back-off conditionscan drastically reduce system efficiency and produce undesired thermalchallenges.

In some applications, such as for example 5G New Radio (NR), it isenvisioned to reduce power output by the amplifiers (e.g., 6 dB orlower) when higher power is not needed. In turn, it is desired that suchreduction of output power can decrease overall power dissipation andtherefore address some of the related thermal challenges discussedabove. When using a balanced amplifier, such as one shown in FIG. 1A, areduction of output power may be provided by a corresponding reductionof an input RF power (e.g., RF amplitude) to the amplifier (e.g.,amplifier of RF_(IN) signal). However, reducing the input RF power tothe balanced amplifier does not affect a DC power through each of thesingle-ended amplifiers (e.g., 130 a, 130 b of FIG. 1A), and thereforedoes not substantially affect efficiency of the balanced amplifier.

Teaching according to the present disclosure allow for reduction of theDC power in a balanced amplifier configuration when operating at areduced power and therefore allow for increased efficiency of thebalanced amplifier when operating at the reduced power.

SUMMARY

According to a first aspect of the present disclosure, an amplifierarrangement configured to operate according to a first mode of operationand a second mode of operation is presented, the amplifier arrangementcomprising: a first amplifier comprising an input and an output; asecond amplifier comprising an input and an output; an input couplercomprising an input port, an input terminated port, and respectiveamplifier input ports coupled to respective inputs of the first and thesecond amplifier; an output coupler comprising an output port, an outputterminated port, and respective amplifier output ports coupled torespective outputs of the first and the second amplifier; wherein duringthe first mode of operation: the first and the second amplifiers areactivated and the amplifier arrangement is configured to operate as abalanced amplifier for amplification of an input RF signal provided atthe input port of the input coupler and generation therefrom of anoutput RF signal provided at the output port of the output coupler, andwherein during the second mode of operation: one of the first and secondamplifiers is deactivated and the other one of the first and secondamplifiers is activated, and the amplifier arrangement is configured tooperate as a single-ended amplifier for amplification of the input RFsignal provided at the input port of the input coupler via the activatedamplifier and generation therefrom of the output RF signal provided atthe output port of the output coupler, and an impedance coupled to aswitching impedance port of the input or output coupler is adjusted, theswitching impedance port comprising one of: the input or outputterminated port, or the respective amplifier input port or therespective amplifier output port associated with the deactivatedamplifier.

According to second aspect of the present disclosure, a method forreducing output power of a balanced amplifier is presented, the methodcomprising: providing a balanced amplifier comprising an input couplerand an output coupler coupled to respective inputs and outputs of afirst and a second amplifier; coupling at least one switching impedancecircuit to a port of the input or output coupler; deactivating one ofthe first or second amplifiers for reducing output power, therebyproviding amplification based on an activated amplifier of the first andthe second amplifiers; and based on the coupling and the deactivating,tuning a frequency response of the amplification by adjusting animpedance value coupled to said port of the input or output coupler.

BRIEF DESCRIPTION OF DRAWINGS

The accompanying drawings, which are incorporated into and constitute apart of this specification, illustrate one or more embodiments of thepresent disclosure and, together with the description of exampleembodiments, serve to explain the principles and implementations of thedisclosure.

FIG. 1A shows a simplified bock diagram of a prior art balancedamplifier comprising input and output couplers.

FIG. 1B shows exemplary internal configuration of a coupler that can beused in the balanced amplifier of FIG. 1A.

FIG. 1C shows two internal conduction paths of the coupler shown in FIG.1B based on a nominal operation of the coupler.

FIG. 1D shows two internal conduction paths of the coupler shown in FIG.1B based on a first degenerative operation of the coupler.

FIG. 1E shows two internal conduction paths of the coupler shown in FIG.1B based on a second degenerative operation of the coupler.

FIG. 2A shows a simplified bock diagram of a balanced amplifieraccording to an exemplary embodiment of the present disclosure forproviding a reduced output power via a deactivated amplification path.

FIG. 2B shows a simplified bock diagram of a balanced amplifieraccording to another exemplary embodiment of the present disclosure forproviding a reduced output power via a deactivated amplification path.

FIGS. 3A, 3B and 3C show various exemplary configurations according tothe present disclosure for turning OFF one or more amplificationelements of a deactivated amplification path.

FIG. 4A shows an exemplary configuration according to the presentdisclosure of impedance switching that can be used in an output couplerof the configurations shown in FIG. 2A and/or FIG. 2B.

FIG. 4B shows an exemplary configuration according to the presentdisclosure of impedance switching that can be used in an input couplerof the configurations shown in FIG. 2A and/or FIG. 2B.

FIG. 4C shows another exemplary configuration according to the presentdisclosure of impedance switching that can be used in an input couplerof the configurations shown in FIG. 2A and/or FIG. 2B.

FIG. 5A shows graphs representative of an insertion loss as a functionof frequency for different impedances coupled to an unused port of theinput coupler of the balanced amplifier shown in FIG. 2A.

FIG. 5B shows graphs representative of an insertion loss as a functionof frequency for different impedances coupled to an unused port of theinput coupler of the balanced amplifier shown in FIG. 2B.

FIG. 5C shows graphs representative of an insertion loss as a functionof frequency for different impedances coupled to an unused port of theoutput coupler of the balanced amplifier shown in FIG. 2B.

FIG. 5D shows graphs representative of an insertion loss as a functionof frequency for different impedances coupled to an unused port of theoutput coupler of the balanced amplifier shown in FIG. 2A.

FIG. 6 is a process chart showing various steps of a method for reducingpower of a balanced amplifier according to an embodiment of the presentdisclosure.

DETAILED DESCRIPTION

Throughout this description, embodiments and variations are describedfor the purpose of illustrating uses and implementations of theinventive concept. The illustrative description should be understood aspresenting examples of the inventive concept, rather than as limitingthe scope of the concept as disclosed herein.

The present disclosure describes electrical circuits in electronicdevices (e.g., cell phones, radios, base stations, etc.) having aplurality of devices, such as for example, transistors (e.g., MOSFETs).Persons skilled in the art will appreciate that such electrical circuitscomprising transistors can be arranged as amplifiers.

As used herein, the expression “operating frequency” can refer to afrequency of a signal being input to a device (such as an amplifier).

As used herein, the expression “center frequency” can refer to areference frequency about which the operating frequency varies. Thecenter frequency may be, for example, associated to a band or channel ofoperation of an RF communication system, and the operating frequency maybe associated to a bandwidth of the band or channel of operation.

FIG. 1B shows exemplary internal configuration of a prior art coupler(100B) that can be used, for example, in the balanced amplifier of FIG.1A, as any of the couplers (110) and/or (120). As can be seen in FIG.1B, the coupler (100B) is a 4-port network comprising respective portsP1, P2, P3 and P4 (also labeled as Port1, Port2, Port3 and Port4 in FIG.1B), wherein any two such ports are coupled to one another via arespective transmission line TL₁ and TL₂, having a respectivecharacteristic impedance Z_(O1) and Z_(O2). As known to a person skilledin the art, the transmission lines TL₁ and TL₂ are designed to providethe respective characteristic impedances Z_(O1) and Z_(O2) based on atarget system impedance (Z_(O)), such as, for example, Z_(O)=50 Ohms.For example, in some embodiments, Z_(O1)=Z_(O) and Z_(O2)=0.707×Z_(O)(e.g., for equal power splitting).

As known to a person skilled in the art, the coupler (100B) shown inFIG. 1B can nominally be used to either divide/split an RF signal at theport P1 to two substantially equal power and out of phase (e.g.,quadrature phase) RF signals at respective ports P2 and P3, or combinetwo substantially equal power and out of phase (e.g., quadrature phase)RF signals at respective ports P2 and P3 to a single RF signal at portP1. Such nominal modes of operation (e.g., split and combine) of thecoupler (100B) may be based on a termination impedance provided at theport P4 that is configured to “isolate” such port from any RF signalflowing through the coupler. As known to a person skilled in the art,such termination impedance may be equal to the system impedance, Z_(O).Furthermore, it should be noted that a ratio of the power splitting(e.g., ratio of powers between P2 and P3) provided by the coupler (100B)may not necessarily be an equal ratio (e.g., 50/50) and may be based onrelative values of the respective characteristic impedances Z_(O1) andZ_(O2). As known to a person skilled in the art, a desired magnitude ofthe power ratio, pRatio_mag, may be provided by designing thetransmission lines TL₁ and TL₂ to have respective impedancesZ_(O1)=Z_(O)*pRatio_mag{circumflex over ( )}0.5 andZ_(O2)=Z_(O)*(pRatio_mag/(1+pRatio_mag)){circumflex over ( )}0.5. Inother words, operation of the balanced amplifier of FIG. 1A may be basedon couplers (110, 120) having a power splitting which is not necessarilyan equal power (e.g., 50/50).

Accordingly, as shown in FIG. 1C, during such nominal modes ofoperation, two separate internal conduction paths, Path2 and Path3, areprovided by the coupler (100B), wherein Path2 provides conductionbetween port P1 and port P2, and Path3 provides conduction between portP1 and port P3. For example, splitting an RF signal at port P1 intoports P2 and P3 is provided by the Path 2 established between port P1and port P2, and the Path 3 established between port P1 and port P3.Likewise, combining RF signals at ports P2 and P3 into port P1 isprovided by the Path 2 established between port P2 and port P1, and thePath 3 established between port P3 and port P1. In other words, each ofthe paths Path2 and Path3 can operate bidirectionally.

With reference back to the prior art configuration of FIG. 1A, it can beseen that a first portion (e.g., half of the power) of the RF_(IN)signal at port P1 of the input coupler (110) flows through Path3 of thecoupler (110), through the (single-ended) amplifier (130 a) foramplification, and through Path2 of the output coupler (120) for output(and combining) at the port P1 of the output coupler (120). Likewise, asecond portion (e.g., half of the power) of the RF_(IN) signal at portP1 of the input coupler (110) flows through Path2 of the coupler (110),through the (single-ended) amplifier (130 b), and through Path3 of theoutput coupler (120) for output (and combining) at the port P1 of theoutput coupler (120). Accordingly, in the prior art configuration shownin FIG. 1A, ports P2 and P3 of either couplers (110, 120) are used ascoupling ports to (differential) input or output of the amplifiers (130a, 130 b), port P1 is used as either input or output of the balancedamplifier, and port P4 is used as the terminating port (coupled to aterminating impedance).

It should be noted that the above description is based on nominal usageof the coupler (100B) according to a configuration wherein the ports P2and P3 are essentially isolated from one another. As known to a personskilled in the art, isolation between ports P2 and P3 is achieved by thecoupler structure that provides a cancelation behavior of signalstraveling through two distinct signal paths between ports P2 and P3,each signal path provided by one or more of the transmission lines(sections) of the coupler structure as shown in FIG. 1B. Such couplerstructure provides 90 degree phase for each section of each signal path,the section based on one transmission line of the coupler structure. Forexample, for a signal entering at port P2, the signal travels throughtwo different transmission paths to port P3. One transmission path thatpasses through a single transmission line (e.g., TL₁ between ports P2and P3) incurs a 90 degree phase offset, while the second transmissionpath that passes through three transmission lines (e.g., TL₂, TL₁, TL₂between ports P2 and P1, P1 and P4, and P4 and P3) incurs a 270 degreephase offset. The summation of signals through the two transmissionpaths at port P3 results in near perfect cancellation at the centerfrequency.

Teachings according to the present disclosure configure the coupler(100B) for a “degenerative” usage, or “degenerative mode”, or“degenerative mode of operation”, wherein an impedance that is coupledto one of the two ports P2 or P3 that is OFF (e.g., OFF port) is used toforce the conduction path away from the OFF port and towards the otherone of the two ports P2 and P3 that is active (e.g., ON port). Suchdegenerative mode of operation according to the present disclosure isprovided by careful configuration of impedances seen at ports P2 or P3(e.g., OFF port) so as to optimize signal transfer from port P1 to portP3 or P2 (e.g., ON port), respectively. Furthermore, such degenerativemode of operation according to the present disclosure may configure theimpedance coupled at the port P4 in view of the impedances at ports P2or P3. According to an exemplary embodiment of the present disclosure, amagnitude of the impedance seen at port P4 may be proportional to amagnitude of the impedance seen at port P3 when the degenerative mode ofoperation diverts a signal path from port P3 towards port P2 (e.g., FIG.1E). According to another exemplary embodiment of the presentdisclosure, a magnitude of the impedance seen at port P4 may beinversely proportional to a magnitude of the impedance seen at port P2when the degenerative mode of operation diverts a signal path from portP2 towards port P3 (e.g., FIG. 1D). During normal, non-degenerativeoperation of the balanced amplifier of FIG. 1A, the input coupler (110)and output coupler (120) have their respective ports, port P2 and portP3, impedances provided by the respective input impedance (shown in FIG.1A as Z_(IN_ON)) and output impedance (shown in FIG. 1A as Z_(OUT_ON))of the amplifiers (130 a, 130 b) during operation (active state) of theamplifiers.

FIG. 1D shows two internal conduction paths, Path3 a and Path3 b, of thecoupler shown in FIG. 1B based on a first degenerative (mode of)operation of the coupler (100B), wherein a first portion of a signalprovided at the port P1 is conducted, through the conduction path, Path3b, from the port P1 to the port P2 and then diverted for output (andcombining) at the port P3; and a second portion of the signal providedat the port P1 is conducted, through the conduction path, Path3 a thatis parallel to Path3 b, from the port P1, through the port P4 for output(and combining) at the port P3. A person skilled in the art wouldclearly understand that the second portion of the signal flows through apath (e.g., Path3 a) similar to one described with respect to FIG. 1C,whereas the first portion flows through the Path3 b that includes anextra transmission line (e.g., TL₁) arranged between ports P2 and P3. Asnoted above, a combination of impedances seen at ports P2 and P4 mayprovide for the signal paths shown in FIG. 1D. Because both signalpaths, Path3 a and Path3 b, shown in FIG. 1D provide conduction betweenports P1 and P3, the combined signal paths may be referred to, in thepresent disclosure, as a Path3 conduction path that as noted above isprovided via a degenerative operation of the coupler (100B), such asPath3=Path3 a//Path3 b (in parallel configuration).

FIG. 1E shows two internal conduction paths, Path2 a and Path2 b, of thecoupler shown in FIG. 1B based on a second degenerative (mode of)operation of the coupler (100B), wherein a first portion of a signalprovided at the port P1 is conducted, through the conduction path, Path2b, from the port P1 to the port P2, and a second portion of the signalprovided at the port P1 is conducted, through the conduction path, Path2a that is parallel to Path2 b, from the port P1, through the port P4 andto port P3, and then diverted for output (and combining) at the port P2.A person skilled in the art would clearly understand that the firstportion of the signal flows through a path (e.g., Path2 b) similar toone described with respect to FIG. 1C, whereas the second portion flowsthrough the Path2 a that includes an extra transmission line (e.g., TL₁)arranged between ports P3 and P2. As noted above, a combination ofimpedances seen at ports P3 and P4 may provide for the signal pathsshown in FIG. 1E. Because both signal paths shown in FIG. 1E provideconduction between ports P1 and P2, the combined signal paths may bereferred to, in the present disclosure, as a Path2 conduction path, thatas noted above is provided via a degenerative operation of the coupler(100B), such as Path2=Path2 a//Path2 b (in parallel configuration).

FIG. 2A shows a simplified bock diagram of a balanced amplifier (200A)according to an exemplary embodiment of the present disclosure forproviding a reduced output power via a deactivated amplification path(e.g., 130 a). As can be clearly understood by a person skilled in theart, the balanced amplifier (200A) has similar elements as onesdescribed above with respect to the configuration shown in FIG. 1A, withsome exceptions, including impedances seen at various ports of the inputcoupler (110) and the output coupler (120) intended for (selective)operation of such couplers according to a degenerative mode of operationdescribed above with respect to FIG. 1D and FIG. 1E when the amplifier(200A) operates at reduced output power. For example, as shown in FIG.2A, during operation at reduced output power, impedances Z_(4IN) at portP4 and Z_(IN_OFF) at port P3 of the input coupler (110), as well asimpedances Z_(4OUT) at port P4 and Z_(OUT_OFF) at port P2 of the outputcoupler (120) may be selectively configured/adjusted.

During a normal (higher output power) operation of the balancedamplifier (200A) of FIG. 2A, amplification is based on a same principleof operation as described above with reference to the configurationshown in FIG. 1A. In other words, during operation for higher outputpower, the input RF signal, RF_(IN), is split by the input coupler (110)into out of phase (e.g., quadrature phase) RF signals, each of thequadrature RF signals amplified via an amplifier (e.g., 130 a, 130 b) ofa corresponding amplification path, each amplified quadrature RF signaloutput to respective ports of the output coupler (120) for(constructive) quadrature re-combining to generate the amplified outputRF signal, RF_(OUT), at the output port P1 of the output coupler (120).Accordingly, the input RF signal, RF_(IN), is coupled to respectiveinputs of amplifiers (130 a, 130 b) via respective Path3 and Path2 ofthe input coupler (110), and respective outputs of the amplifiers (130a, 130 b) are coupled to respective Path2 and Path3 of the outputcoupler (120), while ports P2 and P3 of the input coupler (110) and ofthe output coupler (120) remain substantially isolated.

On the other hand, during a reduced power (reduced output power)operation of the balanced amplifier (200A) of FIG. 2A, the amplifier(130) of one of the amplification paths (e.g., top amplification path130 a) is deactivated and the input and output couplers (110, 120) areconfigured for operation according to a degenerative mode describedabove with reference to FIG. 1D and FIG. 1E. For example, the inputcoupler (110) can be configured for operation according to the Path2 ofthe second degenerative mode shown in FIG. 1E, wherein an impedance at(i.e., coupled to) the port P3 of the input coupler (110) correspondingto an input of the deactivated amplifier (130 a), is modified (from anominal value defined by an active state impedance) to provide a(substantial) coupling between port P3 and the port P2 of the inputcoupler (110). Likewise, the output coupler (120) can be configured foroperation according to the Path3 of the first degenerative mode shown inFIG. 1C, wherein an impedance at the port P2 of the output coupler (120)corresponding to an output of the deactivated amplifier (130 a), ismodified (from a nominal value) to provide a (substantial) couplingbetween port P2 and the port P3 of the output coupler (120). It shouldbe noted that although in a practical implementation there may existsome level of coupling between ports P2 and P3 during a nominaloperation of the coupler (e.g., per FIG. 1C), a level of couplingbetween such ports during the degenerative mode of the coupler (e.g.,per FIGS. 1D and 1E) is substantially higher magnitude and at a levelthat is measurable (e.g., via insertion loss measurement) and providesconsiderable differentiation between operation in the two modes (nominalvs. degenerative). It should be noted that as clearly understood by aperson skilled in the art, during the reduced power operation, theconfiguration shown in FIG. 2A does not operate in a balancedconfiguration, and therefore some advantages provided by such balancesconfiguration may be lost in favor of advantages provided by the reduced(DC) power operation.

With continued reference to FIG. 2A, because ports P2 and P3 of theinput/output couplers (110, 120) are used for coupling to the amplifiers(130 a) and (130 b), in the present disclosure such ports P2 and P3 maybe respectively referred to as Amplifier_A-port and Amplifier_B-port ofa coupler. Likewise, because port P1 is used for coupling of the inputRF_(IN) signal or the output RF_(OUT) signal, in the present disclosuresuch port may be referred to as Input_port or Output_port of a coupler.Finally, the port P4 used to provide a termination impedance to theinput/output couplers (110, 120) may be arbitrarily referred to in thepresent disclosure as isolated/terminated port of a coupler. Using suchdefinitions, and with continued reference to FIG. 2A, the RF_(IN) signaland the RF_(OUT) signals are respectively fed to the Input_Port of theinput coupler (110) and received from the Output_Port of the outputcoupler (120). The isolated/terminated ports of the input coupler (110)and the output coupler (120) are respectively coupled to an adjustableimpedance Z4 _(IN) and Z4 _(OUT) that is configured to selectivelyprovide an impedance value according to a mode of operation (normalpower or reduced power) of the balanced amplifier (200A).Amplifier_B-port and Amplifier_A-port of the input coupler (110) arerespectively coupled to an input of the amplifier (130 a) and an inputof the amplifier (130 b), and Amplifier_A-port and Amplifier_B-port ofthe output coupler (120) are respectively coupled to an output of theamplifier (130 a) and an output of the amplifier (130 b).

With continued reference to FIG. 2A, deactivation of the amplifier (130a) during operation according to the reduced power, may includereduction of a DC power through the amplifier (130 a) and therefore, asclearly understood by a person skilled in the art, may generate aneffective reduction in dissipated power through the amplifier (i.e.,associated with a reduction in a bias DC current through the amplifier).As known to a person skilled in the art, and shown in FIG. 1A and FIG.2A, the amplifiers (130 a, 130 b) may each be an amplifier module thatincludes one or more cascaded amplifiers (stages) having variousamplification levels. For example, each of the amplifiers (130 a, 130 b)may include a plurality of cascaded stages, such as, for example, threecascaded stages (e.g., (130 a 1, 130 a 2, 130 a 3) and (130 b 1, 130 b2, 130 b 3) shown in FIG. 2A, also referred to as, for example, an inputstage, an intermediate stage, and a final stage), wherein amplificationprovided by each such stage may be based on a DC current (e.g., biascurrent) through such stage based on, for example, a DC supply coupledto the stage, as shown in FIGS. 3A, 3B and 3C.

According to an exemplary embodiment of the present disclosure,deactivation of an amplifier used in the configuration of FIG. 2A, suchas, for example, deactivation of the amplifier (130 a), may includedeactivating one, or more, or all of the amplification stages of theamplifier, wherein deactivation of one stage comprises of removing a DCcurrent flow through the stage, such as, for example, removing DC powerto the stage. Accordingly, total DC power through the amplifier (e.g.,130 a) is reduced (case where not all stages are deactivated) or nulled(case where all stages are deactivated). FIGS. 3A, 3B and 3C show someexemplary configurations for activating/deactivating the amplifier (130a) shown in FIG. 2A via switches (e.g., SW₁, SW₂, SW₃, SW₁₃₀) that canselectively couple/decouple one or more stages of the amplifier to/froma supply power, thereby removing a DC current flow through theamplifier. It should be noted that deactivating of the amplifier (130 a)can be provided by deactivating at least one stage (e.g., 130 a 1, 130 a2, 130 a 3) of the amplifier (130 a), whereas activating of theamplifier (130 a) requires that all such stages be activated.

With reference to FIG. 3A and FIG. 3B, such figures show an exemplaryconfiguration wherein each of the stages (130 a 1, 130 a 2, 130 a 3) ofthe amplifier (130 a) is coupled to a supply power, V_(DD), via arespective switch (SW₁, SW₂, SW₃). Accordingly, the configurations shownin FIG. 3A and FIG. 3B allow for selective activation and deactivationof each stage of the amplifier (130 a). As shown in FIG. 3A, the inputstage (130 a 1) is deactivated by opening switch SW₁, while theintermediate stage (130 a 2) and the output stage (130 a 3) remainactivated (switches SW₂ and SW₃ closed). According to an exemplaryembodiment of the present disclosure, deactivation of the amplifier (130a) shown in the configuration of FIG. 2A can include deactivationaccording to FIG. 3A or FIG. 3B. Accordingly, in both the activated, anddeactivated according to FIG. 3A, conditions of the amplifier (130 a),the impedance Z_(OUT_OFF) presented to the port P2 of the output coupler(120) may remain unchanged and provided by the output stage (130 a 3) ofthe amplifier (130). Likewise, in both the activated, and deactivatedaccording to FIG. 3B, conditions of the amplifier (130 a), the impedanceZ_(IN_OFF) presented to the port P3 of the input coupler (110) mayremain unchanged and provided by the input stage (130 a 1) of theamplifier (130 a). Although not shown in the figures, deactivation ofthe amplifier (130 a) may also include, for example, deactivation of theintermediate stage (130 a 2) while leaving the other two stages (130 a1, 130 a 3) activated such as to present a same impedance to thecouplers (110, 120) in both activated and deactivated conditions of theamplifier (130 a).

With reference to FIG. 3C, such figure shows an exemplary configurationwherein each of the stages (130 a 1, 130 a 2, 130 a 3) of the amplifier(130 a) is coupled to a supply power, V_(DD), via a single (global)switch (SW₁₃₀). Accordingly, the configuration shown in FIG. 3C does notallow for selective activation and deactivation of each stage of theamplifier (130 a), rather for a global activation and deactivation ofthe amplifier (130 a) wherein all of the stages are either activated ordeactivated. According to an exemplary embodiment of the presentdisclosure, deactivation of the amplifier (130 a) shown in theconfiguration of FIG. 2A can include deactivation according to FIG. 3C.Accordingly, when the amplifier (130 a) is deactivated according to FIG.3C, the impedances Z_(OUT_OFF) and Z_(IN_OFF) presented to therespective ports P2 of the output coupler (120) and P3 of the inputcoupler (110) by the amplifier (130 a) changes when compared to theimpedance presented to the same ports when the amplifier (130 a) isactive (i.e., activated). As will be described later with respect toFIGS. 4A. 4B and 4C, teachings according to the present disclosure allowselective switching of impedance values at any one of the ports P2and/or P3 (e.g., Amplifier_A-port and/or Amplifier_B-port) that wouldotherwise be coupled to a deactivated amplifier (e.g., 130 a). In otherwords, with reference to FIG. 2A, teachings according to the presentdisclosure allow selective setting of the impedances Z_(IN_OFF) andZ_(OUT_OUT) for operation of the input and output couplers (110, 120)according to the degenerative modes described above with reference toFIG. 1D and FIG. 1E.

FIG. 2B shows a simplified bock diagram of a balanced amplifier (200B)according to an exemplary embodiment of the present disclosure forproviding a reduced output power via a deactivated amplification path(e.g., 130 b). As can be clearly understood by a person skilled in theart, the configuration shown in FIG. 2B can be considered as the dual ofthe configuration shown in FIG. 2A, wherein the reduced output power isprovided via deactivating of the amplifier (130 b) instead of theamplifier (130 a). Accordingly, impedances seen at various ports of theinput coupler (110) and the output coupler (120) are intended for(selective) operation of such couplers according to a degenerative modeof operation described above with respect to FIG. 1D and FIG. 1E whenthe amplifier (200B) operates at reduced output power. For example, asshown in FIG. 2B, during operation at reduced output power, impedancesZ_(4IN) at port P4 and Z_(IN_OFF) at port P2 of the input coupler (110),as well as impedances Z_(4OUT) at port P4 and Z_(OUT_OFF) at port P3 ofthe output coupler (120) may be selectively configured/adjusted. Aperson skilled in the art would clearly understand principle ofoperation of the configuration shown in FIG. 2B based on the abovedescription with reference to FIG. 2A as well as FIGS. 3A, 3B and 3C. Inparticular, the person skilled in the art would clearly understand thatduring the reduced output power configuration per FIG. 2B, impedances atports P2 and P4 of the input coupler (110) configure such coupler tooperate according to the Path3 of the first degenerative mode shown inFIG. 1D, and impedances at ports P3 and P4 of the output coupler (120)configure such coupler to operate according to the Path2 of the seconddegenerative mode shown in FIG. 1E. Furthermore, the person skilled inthe art would clearly understand that any of the configurationsdescribed above with reference to FIGS. 3A, 3B and 3C may be used foractivation and deactivation of the amplifier (130 b). Finally, a personskilled in the art would clearly understand that any of the reducedoutput power configurations shown in FIG. 2A and FIG. 2B can be appliedon the prior art configuration of FIG. 1A. In other words, according toan embodiment of the present disclosure, either one of the twoamplifiers (130 a) or (130 b) may be deactivated for provision of areduced power output mode of operation according to the presentdisclosure.

FIG. 4A shows an exemplary configuration (400A) according to the presentdisclosure of impedance switching that can be used to present differentimpedances to an output coupler (120) of the configurations shown inFIG. 2A and/or FIG. 2B. In particular, FIG. 4A shows a switchableimpedance (410 a) coupled to a port (e.g., P2, Amplifier_A-port) of theoutput coupler (120). As can be seen in FIG. 4A, the switchableimpedance (410 a) may include a (SPDT) switch, SW_(OUT), coupled at aswitching terminal of the switch SW_(OUT) to the port (e.g., P2,Amplifier_A-port) of the output coupler (120), at a first throw of theswitch SW_(OUT) to an output node of an amplifier (e.g., 130 a), and ata second throw of the switch SW_(OUT) to an impedance, Z_(OUT).Furthermore, as shown in FIG. 4A, an adjustable/configurable impedance,Z_(4OUT), is coupled to port P4 (e.g., isolated/terminated port) of theoutput coupler (120). Such impedance switching according to the presentdisclosure may allow switching of different impedances to the ports(e.g., 2 and 4) of the output coupler (120) when operating according tothe reduced output power mode of FIG. 2A (or FIG. 2B). Configurationcontrol for the impedance switching may be provided via control lines(not shown) originating from a signal/configuration aware controller,such as, for example, a transceiver. It should be noted that as known toa person skilled in the art, an impedance, such as Z_(OUT) or Z_(4OUT),may be a purely resistive, purely reactive, or a combination of thereof.

With continued reference to FIG. 4A, an effective impedance Z_(OUT_OFF)coupled to an Amplfier_A-port (e.g., P2 per FIG. 4A) associated with adeactivated amplifier (e.g., 130 a) can be set to other than an outputimpedance of the deactivated amplifier (e.g., 130 a), therebycontrolling operation of the output coupler (e.g., 120) according to anyof the modes described above with reference to FIG. 1D or FIG. 1E. Forexample, assuming that the reduced output power mode of operation isprovided via deactivating the amplifier (130 a) as shown in FIG. 4A,then, during operation in the reduced output power mode, the switchSW_(OUT) couples the port P2 (Amplifier_A-port) of the output coupler(120) to the impedance, Z_(OUT); and during operation in the normal mode(higher output power), the switch SW_(OUT) couples the port P2(Amplifier_A-port) of the output coupler (120) to the output of theamplifier (130 a). Furthermore, the controller (e.g., transceiver) maycontrol the adjustable/configurable impedance, Z_(4OUT), to providedifferent impedances between operation in the normal mode and operationin the reduced output power mode. FIG. 4A shows additional detail for anexemplary implementation of the adjustable/configurable impedance,Z_(4OUT), including a single-pole multiple-throw switch SW_(OUT) that isconfigured to selectively couple one of a plurality (e.g., integernumber n) of fixed impedances (Z4 _(OUT1), . . . Z_(4OUTn)) to theisolated/terminated port (i.e., port P4) of the output coupler (120). Itshould be noted that such fixed impedances may include a short and/or anopen.

According to an exemplary embodiment of the present disclosure, theimpedance, Z_(OUT) may also be adjustable/configurable (e.g., per detailof Z_(4OUT) shown in FIG. 4A). In other words, during operation in thereduced output power mode, operation (e.g., RF response) of the outputcoupler (120) may be controlled by adjusting an impedance valuepresented at the Amplifier_A-port (e.g., port P2). Additionally, or inthe alternative, during operation in the reduced output power mode,operation (e.g., RF response) of the output coupler (120) may becontrolled by adjusting an impedance value of Z_(4OUT) presented at theisolated/terminated port (i.e., port P4). As described above,adjusting/configuring of the impedances presented at theAmplifier_A-port and the isolated/terminated port of the coupler may beused to provide different RF responses of the output coupler (120) asshown in FIGS. 5C and 5D later described. According to some exemplaryembodiments of the present disclosure, such adjusting/configuring may bein view of, for example, a desired linear or inversely proportionalrelationship between respective impedance magnitudes. It should be notedthat although the above description with reference to FIG. 4A isexemplified with relation to the reduced output power configurationshown in FIG. 2A, same description equally applies to the reduced outputpower configuration shown in FIG. 2B by replacing the amplifier (130 a)with the amplifier (130 b) and the port P2 (Amplifier_A-port) with theport P3 (Amplifier_B-port).

FIG. 4B shows an exemplary configuration (400B) according to the presentdisclosure of impedance switching that can be used to present differentimpedances to an input coupler (110) of the configurations shown in FIG.2A and/or FIG. 2B. In particular, FIG. 4B shows a switchable impedance(410 b) coupled to a port (e.g., P3, Amplifier_B-port) of the inputcoupler (110) and an adjustable/configurable impedance, Z4 _(IN) that iscoupled to port P4 (e.g., isolated/terminated port) of the input coupler(110). A person skilled in the art would clearly see parallels betweenthe configuration (400B) shown in FIG. 4B and the configuration (400A)described above with reference to FIG. 4A and clearly realize that theconfiguration (400B) is the dual of the configuration (400A) applicableto the input coupler (110). Accordingly, description related to FIG. 4Acan be applied to FIG. 4B, mutatis mutandis.

FIG. 4C shows yet another exemplary configuration (400C) according tothe present disclosure of impedance switching that can be used topresent different impedances to an input coupler (110), as well to anoutput coupler (120), of the configurations shown in FIG. 2A and/or FIG.2B. In particular, FIG. 4C shows a switchable impedance (410 c) coupledto a port (e.g., P3, Amplifier_B-port) of the input coupler (110) and anadjustable/configurable impedance, Z_(4IN) that is coupled to port P4(e.g., isolated/terminated port) of the input coupler (110). Theswitching impedance configuration shown in FIG. 4C is different fromones shown in FIGS. 4A and 4B in that, in the configuration of FIG. 4C,a coupling between a port (e.g., P3) of the coupler (e.g., 110) and acorresponding amplifier (e.g., 130 a) is maintained in both modes (e.g.,the normal and reduced output power) of operation, and impedanceswitching is provided by (selectively) coupling an impedance (e.g.,Z_(IN)) at a node that connects the amplifier to the coupler via an SPDTswitch, SW_(IN). As clearly understood by a person skilled in the art,such selective coupling of the impedance (e.g., Z_(IN)) can be performedto an input of the deactivated amplifier (e.g., 130 a) irrespective ofan activated or deactivated state of a corresponding input stage (e.g.,130 a 1) of the amplifier. On the other hand, an impedance switchingaccording to the configuration of FIG. 4C may only be used at an outputof the deactivated amplifier (e.g., 130 a) if deactivation of suchamplifier includes deactivating of its output stage (e.g., 130 a 3). Theimpedance switching configuration shown in FIG. 4C switches impedancepresented to a port (e.g., P2 and/or P3) of a coupler (e.g., inputand/or output) by introducing (a shunted) impedance at a node thatconnects the port of the coupler to the amplifier. In other words, aneffect of the switched impedance is to present an effective impedance tothe port of the coupler that is a combination of an impedance presentedby the amplifier and the switched impedance.

Based on FIGS. 4A, 4B and 4C, adjusting/configuring of the impedancespresented at the Amplifier_A-port and/or Amplifier_B-port, and theisolated/terminated port, of any one of the input and/or output coupler(110, 120) may be used to provide different RF responses of the balancedamplifier configuration according to the present disclosure whenoperating in reduced output power mode. Such different RF responses maybe provided by individually adjusting RF response of the input coupler(110) and/or of the output coupler (120), wherein a combined effect ofsuch adjusting is observed at the output port P1 of the output coupler(120).

FIGS. 5A and 5B show graphs representative of effects on RF response(e.g., insertion loss vs. frequency) of the input coupler (110) forPath2 (e.g., FIG. 2A) and Path3 (e.g., FIG. 2B) configurations fordifferent values impedances at the isolated/terminated port P4 of theinput coupler (110). Likewise, FIGS. 5C and 5D show graphsrepresentative of effects on RF response (e.g., insertion loss vs.frequency) of the output coupler (120) for Path2 (e.g., FIG. 2B) andPath3 (e.g., FIG. 2A) configurations for different values impedances atthe isolated/terminated port P4 of the output coupler (120). As can beclearly taken from these figures, adjustment of impedance values(Z_(4IN), Z_(4OUT)) seen at the isolated/terminated port P4 for each ofthe input and output couplers (110, 120) shown in FIGS. 2A and 2B can beused to affect/tune a frequency response of the balanced amplifierconfiguration according to the present teachings when operating in thereduced output power mode. Such tuning may include, for example, i)tuning to reduce sensitivity in amplitude response of one or bothcouplers with respect to (unintentional) varying of the impedance valueat the port P4 (e.g., due to for example uncontrollable parameters suchas process/temperature/other variation), or ii) control RF amplitudeoutput by a path (e.g., Path2 and/or Path3), or iii) any otherequalizing of the RF response based on design goals. It should be notedthat although not included, additional graphs may be generatedrepresenting effects on RF response of the input/output couplers (110,120) for Path2 and Path3 configurations for different values impedancesat the P2 and P3 ports (Amplifier_A-port and Amplifier_B-port) of theinput/output couplers (110, 120).

FIG. 6 is a process chart (600) showing various steps of a method forreducing output power of a balanced amplifier. As can be seen in FIG. 6,such steps comprise: providing a balanced amplifier comprising an inputcoupler and an output coupler coupled to respective inputs and outputsof a first and a second amplifier, per step (610); coupling at least oneswitching impedance circuit to a port of the input or output coupler,per step (620); deactivating one of the first or second amplifiers forreducing output power, thereby providing amplification based on anactivated amplifier of the first and the second amplifiers, per step(630); and based on the coupling and the deactivating, tuning afrequency response of the amplification by adjusting an impedance valuecoupled to said port of the input or output coupler, per step (640).

It should be noted that the various embodiments of the balancedamplifier configuration according to the present disclosure, may beimplemented as a monolithically integrated circuit (IC) according to anyfabrication technology and process known to a person skilled in the art.

Applications that may include the novel apparatus and systems of variousembodiments include electronic circuitry used in high-speed computers,communication and signal processing circuitry, modems, single ormulti-processor modules, single or multiple embedded processors, dataswitches, and application-specific modules, including multilayer,multi-chip modules. Such apparatus and systems may further be includedas sub-components within a variety of electronic systems, such astelevisions, cellular telephones, personal computers (e.g., laptopcomputers, desktop computers, handheld computers, tablet computers,etc.), workstations, radios, video players, audio players (e.g., mp3players), vehicles, medical devices (e.g., heart monitor, blood pressuremonitor, etc.) and others. Some embodiments may include a number ofmethods.

The term “amplifier” as used in the present disclosure is intended torefer to amplifiers comprising single or stacked transistors configuredas amplifiers, and can be used, for example, as power amplifiers (PAs)and/or low noise amplifiers (LNAs). An amplifier can refer to a devicethat is configured to amplify a signal input to the device to produce anoutput signal of greater magnitude than the magnitude of the inputsignal. Stacked transistor amplifiers are described for example in U.S.Pat. No. 7,248,120, issued on Jul. 24, 2007, entitled “StackedTransistor Method and Apparatus”, U.S. Pat. No. 7,123,898, issued onOct. 17, 2006, entitled “Switch Circuit and Method of Switching RadioFrequency Signals”, U.S. Pat. No. 7,890,891, issued on Feb. 15, 2011,entitled “Method and Apparatus Improving Gate Oxide Reliability byControlling Accumulated Charge”, and U.S. Pat. No. 8,742,502, issued onJun. 3, 2014, entitled “Method and Apparatus for use in ImprovingLinearity of MOSFETs Using an Accumulated Charge Sink—Harmonic WrinkleReduction”, the disclosures of which are incorporated herein byreference in their entirety. As used herein, the term “amplifier” canalso be applicable to amplifier modules and/or power amplifier moduleshaving any number of stages (e.g., pre-driver, driver, final), as knownto those skilled in the art.

The term “MOSFET”, as used in this disclosure, means any field effecttransistor (FET) with an insulated gate and comprising a metal ormetal-like, insulator, and semiconductor structure. The terms “metal” or“metal-like” include at least one electrically conductive material (suchas aluminum, copper, or other metal, or highly doped polysilicon,graphene, or other electrical conductor), “insulator” includes at leastone insulating material (such as silicon oxide or other dielectricmaterial), and “semiconductor” includes at least one semiconductormaterial.

As should be readily apparent to one of ordinary skill in the art,various embodiments of the invention can be implemented to meet a widevariety of specifications. Unless otherwise noted above, selection ofsuitable component values is a matter of design choice and variousembodiments of the invention may be implemented in any suitable ICtechnology (including but not limited to MOSFET structures), or inhybrid or discrete circuit forms. Integrated circuit embodiments may befabricated using any suitable substrates and processes, including butnot limited to standard bulk silicon, silicon-on-insulator (SOI), andsilicon-on-sapphire (SOS). Unless otherwise noted above, the inventionmay be implemented in other transistor technologies such as bipolar,GaAs HBT, GaN HEMT, GaAs pHEMT, and MESFET technologies. However, theinventive concepts described above are particularly useful with anSOI-based fabrication process (including SOS), and with fabricationprocesses having similar characteristics. Fabrication in CMOS on SOI orSOS enables low power consumption, the ability to withstand high powersignals during operation due to FET stacking, good linearity, and highfrequency operation (i.e., radio frequencies up to and exceeding 50GHz). Monolithic IC implementation is particularly useful sinceparasitic capacitances generally can be kept low (or at a minimum, keptuniform across all units, permitting them to be compensated) by carefuldesign.

Voltage levels may be adjusted or voltage and/or logic signal polaritiesreversed depending on a particular specification and/or implementingtechnology (e.g., NMOS, PMOS, or CMOS, and enhancement mode or depletionmode transistor devices). Component voltage, current, and power handlingcapabilities may be adapted as needed, for example, by adjusting devicesizes, serially “stacking” components (particularly FETs) to withstandgreater voltages, and/or using multiple components in parallel to handlegreater currents. Additional circuit components may be added to enhancethe capabilities of the disclosed circuits and/or to provide additionalfunctionality without significantly altering the functionality of thedisclosed circuits.

A number of embodiments according to the present disclosure have beendescribed. It is to be understood that various modifications may be madewithout departing from the spirit and scope of such embodiments. Forexample, some of the steps described above may be order independent, andthus can be performed in an order different from that described.Further, some of the steps described above may be optional. Variousactivities described with respect to the methods identified above can beexecuted in repetitive, serial, or parallel fashion.

It is to be understood that the foregoing description is intended toillustrate and not to limit the scope of the disclosure, which isdefined by the scope of the following claims, and that other embodimentsare within the scope of the claims. (Note that the parenthetical labelsfor claim elements are for ease of referring to such elements, and donot in themselves indicate a particular required ordering or enumerationof elements; further, such labels may be reused in dependent claims asreferences to additional elements without being regarded as starting aconflicting labeling sequence).

1. An amplifier arrangement configured to operate according to a firstmode of operation and a second mode of operation, the amplifierarrangement comprising: a first amplifier comprising an input and anoutput; a second amplifier comprising an input and an output; an inputcoupler comprising an input port, an input terminated port, andrespective amplifier input ports coupled to respective inputs of thefirst and the second amplifier; an output coupler comprising an outputport, an output terminated port, and respective amplifier output portscoupled to respective outputs of the first and the second amplifier;wherein during the first mode of operation: the first and the secondamplifiers are activated and the amplifier arrangement is configured tooperate as a balanced amplifier for amplification of an input RF signalprovided at the input port of the input coupler and generation therefromof an output RF signal provided at the output port of the outputcoupler, and wherein during the second mode of operation: one of thefirst and second amplifiers is deactivated and the other one of thefirst and second amplifiers is activated, and the amplifier arrangementis configured to operate as a single-ended amplifier for amplificationof the input RF signal provided at the input port of the input couplervia the activated amplifier and generation therefrom of the output RFsignal provided at the output port of the output coupler, and animpedance coupled to a switching impedance port of the input or outputcoupler is adjusted, the switching impedance port comprising one of: theinput or output terminated port, or the respective amplifier input portor the respective amplifier output port associated with the deactivatedamplifier.
 2. The amplifier arrangement according to claim 1, whereinadjustment of said impedance is based on a desired frequency response ofthe amplifier arrangement during operation in the second mode.
 3. Theamplifier arrangement according to claim 1, wherein adjustment of saidimpedance is provided by a switching impedance circuit that includes aswitch configured to selectively couple a terminating impedance to theswitching impedance port.
 4. The amplifier arrangement according toclaim 3, wherein the terminating impedance has a variable impedancevalue.
 5. The amplifier arrangement according to claim 3, wherein theswitch is a single-pole multi-throw switch that is configured toselectively couple one or more additional terminating impedances to theswitching impedance port.
 6. The amplifier arrangement according toclaim 3, wherein the switching impedance port comprises the respectiveamplifier input port or the respective amplifier output port associatedwith the deactivated amplifier, during the second mode of operation, theswitch decouples the respective amplifier input port or the respectiveamplifier output port from the deactivated amplifier.
 7. The amplifierarrangement according to claim 1, wherein deactivation of thedeactivated amplifier comprises reduction of a DC power to thedeactivated amplifier.
 8. The amplifier arrangement according to claim7, wherein each of the first amplifier and the second amplifiercomprises a plurality of cascaded amplification stages, and thereduction of the DC power comprises removal of the DC power to at leastone stage of the plurality of cascaded amplification stages.
 9. Theamplifier arrangement according to claim 8, wherein the removal of theDC power is provided via a switch that is configured to selectivelydecouple DC power from the at least one stage independently from otherstages.
 10. The amplifier arrangement according to claim 8, wherein theat least one stage is an input stage of the plurality of cascadedamplification stages.
 11. The amplifier arrangement according to claim8, wherein the at least one stage is an output stage of the plurality ofcascaded amplification stages.
 12. The amplifier arrangement accordingto claim 8, wherein the at least one stage is an input stage and anoutput stage of the plurality of cascaded amplification stages.
 13. Theamplifier arrangement according to claim 1, wherein deactivation of thedeactivated amplifier comprises removal of the DC power to thedeactivated amplifier.
 14. The amplifier arrangement according to claim2, wherein the switching impedance port comprises: the input terminatedport, and the respective amplifier input port associated with thedeactivated amplifier.
 15. The amplifier arrangement according to claim14, wherein said desired frequency response is tuned based on: amagnitude of the adjusted impedance at the input terminated port that islinear with respect of a magnitude of the adjusted impedance at therespective amplifier input port associated with the deactivatedamplifier.
 16. The amplifier arrangement according to claim 14, whereinsaid desired frequency response is tuned based on: a magnitude of theadjusted impedance at the input terminated port that is inverselyproportional with respect of a magnitude of the adjusted impedance atthe respective amplifier input port associated with the deactivatedamplifier.
 17. The amplifier arrangement according to claim 1, whereineach of the input coupler and the output coupler comprises one of abranch-line coupler or a hybrid coupler.
 18. The amplifier arrangementaccording to claim 1, wherein the amplifier arrangement ismonolithically integrated.
 19. The amplifier arrangement according toclaim 18, wherein the amplifier arrangement is monolithically integratedby using a fabrication technology comprising one of: a)silicon-on-insulator (SOI) technology, and b) silicon-on-sapphiretechnology (SOS).
 20. An electronic module comprising the amplifierarrangement according to claim
 18. 21. A phase array element comprisingthe amplifier arrangement according to claim
 18. 22. A method forreducing output power of a balanced amplifier, the method comprising:providing a balanced amplifier comprising an input coupler and an outputcoupler coupled to respective inputs and outputs of a first and a secondamplifier; coupling at least one switching impedance circuit to a portof the input or output coupler; deactivating one of the first or secondamplifiers for reducing output power, thereby providing amplificationbased on an activated amplifier of the first and the second amplifiers;and based on the coupling and the deactivating, tuning a frequencyresponse of the amplification by adjusting an impedance value coupled tosaid port of the input or output coupler.